End Fed HF Antennas

[Chip Fetrow]

ANY end fed or shunt fed antenna is going to need a substantial ground system, or counterpoise.

Broadcasters are required to install 120 quarter-wave (or longer) radiators spaced equally around the base of each vertical radiator.   Before education, I felt this was extreme overkill, but it turns out it is not.  Ground rods mean nearly nothing for RF, but are extremely important for lightning protection.

Dipoles and loops don’t “need” RF grounds, only lightning grounds, but RF grounds can change the departure angle if the antenna is less than 1 wave-length above the earth.

I have used loops on the ham bands.  My results have been mixed.  They seem to be able to have their positions adjusted to avoid some noise.  They generally have very high Qs, which is not an issue for CW, but can be for voice, especially DSB AM.

I am assuming you know there was a loop article in _QST_ fairly recently.  If you haven’t seen it, I recommend it.

—chip

On Oct 1, 2014, at 1:00 PM, tacos-request at amrad.org wrote:

> Message: 2
> Date: Wed, 01 Oct 2014 09:31:07 -0400
> From: kf4hcw <kf4hcw at lifeatwarp9.com>
> To: tacos at amrad.org
> Subject: Re: End Fed HF Antennas
> 
> On 2014-09-30 18:35, R Cramer wrote:
>> Does anyone have any practical experience with end fed HF antennas
>> capable of handling 200W PEP or there abouts.  Higher power labels is
>> also OK.
> 
> I recently did a bit of reading on the subject before deciding to erect
> a vertical loop instead. The biggest reasons being:
> 
> End fed antennas tend to take up a lot of space.
> End fed antennas, especially of any power, require significant
> counter-poise mechanisms.
> 
> I have used end fed antennas with lower power in the past with mixed
> results -- usually ad-hoc wire antennas at field-day ops.
> 
> Hope this helps,
> _M
> 
> kf4hcw
> Pete McNeil
> lifeatwarp9.com/kf4hcw